Lockwood & Co interactive Halloween story: The Dagger in the Desk, part 3

Jonathan Stroud, author of the Bartimaeus trilogy, is writing an exclusive interactive story for Halloween based on the intrepid ghost hunters from his latest book, Lockwood & Co - but he needs your help!

Each day we'll be publishing an instalment of the story along with a way for you to get involved and influence the story. Read the third, thrilling instalment here and place your vote NOW!

Can you see this ghost? You must be a child... Photograph: Arthur Tress/Getty Images

"We sit tight," Lockwood said. "It's loud, it's scary, but it's not actually attacking us directly. If it comes in the room, that's a different matter. Wait and see."

Even as he spoke a third colossal bang resounded on the door. Flakes of plaster fell from the ceiling and the floor shuddered. George and I flinched back inside the circle. We raised our rapiers, tensed our muscles, waited –

Waited…

Nothing came through.

Silence fell outside the door. A pressure lifted from the room. The little trails of ghost-fog dwindled and were gone.

We each exhaled long and loudly. I hadn't realised I'd been holding my breath.

"Temp's back to ten degrees," George reported.

Lockwood nodded. "It's over. For now." He stepped from the circle, strode to the door and flung it open. We emerged into the darkened corridor, shining our torches all around. Straight ahead, and to left and right, the passages stretched away. All was still.

"Nothing," George said.

"Not quite," Lockwood said soberly. "Look at this." He angled his torch beam at the wall beside the door, shining it on the wooden plate, the one that said 'Ernest Potts Memorial Library'. The sign didn't look quite as smart as it had before: two great deep gashes had been scored diagonally across the wood, carving through the words. A knife might have done it. Or claws. Or long sharp fingernails. There were lots of possibilities, and none of them too pleasant.

"Is it just me," I said, "or is something not very happy about this nice new library?"

George was squinting at the sign through his thick round glasses. "Either that or it doesn't like this Ernest Potts geezer. Look at the way his name's sliced up."

I nodded. "Maybe it took exception to his ridiculous facial hair. I know I did."

"Whatever the reason," Lockwood said, "I don't feel that the library is quite at the centre of the haunting. Our readings weren't strong enough inside. The Source must be somewhere else."

Oh, did I mention Sources before? Here's the thing about ghosts, you see. They don't just float about wherever they like. All of them are tied to a specific thing or place – the spot where they died, something important to them in life, or (most often) their bodily remains. We call this tethering point 'the Source', and that's what agents look for. Find it and destroy it, or seal it up with silver – and that's the end of the haunting. Then you can all go home for tea.

"We'd better check out that classroom now," Lockwood was saying.

"Take a look at this mysterious knife, which – Yes, George? What is it?"

George was jiggling about urgently. Either he was suddenly caught short, or he'd had an idea. Or both. Sometimes the two did go together. Whichever, it was best not to ignore him.

"I might hang on in the library, if that's all right," he said. "I want to see if there's a book about the school's history, or some old school magazines or something. I'd like to discover a bit more about old headmaster Potts if I can. You never know, it might come in useful."

"Of course. You don't need to hold my hand. I can lug anything I find inside the chains and read them in there. I'll be absolutely safe. See you in a bit."

George went back into the library. Lockwood and I set off down the left-hand passage. We were once again in an old portion of the school, with walls of panelling and plaster. A number of doors opened on our left and we checked them briefly as we went. The first was a storeroom, filled with mops, vacuum cleaners and stacks of toilet roll. The temperature was chilly here: scarcely seven degrees. The next was little more than a walk-in cupboard, containing paper, pens and other stationary. It too was very cold. The third, the boy's toilets, was niffy, but much warmer – almost twelve degrees. The fourth –

The fourth was an open door. We didn't need to read its sign to know it was the one we sought. Its window panel had been smashed; bright shards of glass glinted in our torchlight, and crunched beneath our boots as we entered the room.

Everywhere was evidence of the pupils' rapid departure the day before: books and pencil-cases littering the table, bags and coats lying crumpled on floor. At the front of the class, the teacher's chair lay upended. Close by, jutting from the side of the desk that faced the door, we found the object that had so terrified Mr Whitaker.

It was a long, thin-bladed knife. The hilt was wound with leather strips, very old and frayed. Fragments of grey cobwebs hung from it too, swaying slightly in small movements of the air.

"That's not an ordinary knife," I said. "That's a dagger."

"You know what it looks like to me?" Lockwood said slowly. "An old military weapon. If I had to guess, I'd say First World War issue, the kind all soldiers carried."

"Well, where's it come from?"

"Answer that, and we find our ghost." Lockwood straightened. "Listen, Lucy – I'm going to double-check further down the corridor. I'm pretty sure there'll be nothing to find: I think the Source is between here and the library. I'll be back in a minute, but while I'm gone, just start some readings in the classroom, would you?"

"Sure."

He slipped out the door and was gone into the dark. I scarcely noticed him go. I was too busy staring at the dagger in the desk. One of my Talents, you see, is that of Touch. Sometimes, if I hold an object that has some kind of psychic charge, I feel or hear things associated with its past. Not every time. It doesn't always work. And if the psychic charge is too strong, it can be uncomfortable or even dangerous for me. But the insights can be useful.

I stared at the dagger and wondered if I should risk it.

What should Lucy do now?

80%

Touch the dagger

9%

Ignore the dagger, do what Lockwood said and explore the rest of Class 2A